An electrical stimulation implant has helped four paralyzed men regain the ability to move their legs.

The device, called an epidural spine stimulator, was implanted in the men as part of a study undertaken by the University of California, Los Angeles (UCLA) and the University of Louisville.

One of the patients in the study, Kent Stephenson, is from Mount Pleasant, Texas. At 21, he was involved in a motocross accident that left him without sensation or motor control from the chest down. Today, he can move his legs, stand on his own and distinguish between types of touch. In addition, he has regained sexual function, bowel control and bladder control.

In a video documenting his progress, Stephenson told the camera, “I feel like we’ve conquered a lot of things people thought were impossible.”

Only four men were involved in this study — meaning that so far, the success rate is 100 percent. A researcher told USA Today that it was too early to determine how effective the treatment would be for the general population.

Still, all four of the men had complete spinal cord injuries, and today all four are able to move their legs. One of the researchers behind the project was quoted as saying, “The belief that no recovery is possible and complete paralysis is permanent has been challenged.”

An article from CNN emphasized that the recovery of sexual function and bowel and bladder control are especially significant for many people who are paralyzed. According to the CNN report, a survey showed that regaining these functions was more important to most paralyzed people than regaining the ability to walk.

According to a news release from UCLA, nearly 1.3 million Americans suffer some form of paralysis associated with a spinal cord injury.

The study was funded in part by Christopher and Dana Reeve Foundation, named for the deceased Superman actor Christopher Reeve, who was paralyzed nearly 20 years ago after an equestrian accident.